无法得到'不相等'操作数识别的char[重复]

Question

编程新手，刚刚开始使用Java。我拿不到那张票要使用字符的操作数。这与while循环有关。即使放置了正确的输入。循环不断地说，这是一个无效的输入，尽管正确的输入被放置。

输入被正确识别并转换为大写。但是同时循环不起作用。任何建议将不胜感激！

    Scanner keyboard = new Scanner(System.in); //Create object to read user data

    System.out.println("Please enter your age between 1 - 110");
    age = keyboard.nextInt();
    while((age < 1) || (age > 110)){
        System.out.println("Error please input a valid age");
        System.out.println("");
        System.out.println("Please enter your age between 1 - 110");
        age = keyboard.nextInt();
    }

    System.out.println("Please enter this person's gender (M/F)");
    gender = keyboard.next().charAt(0);
    gender = Character.toUpperCase(gender); // Convert all inputted character to upper case

    while((gender != 'M') || (gender != 'F')){
        System.out.println("Error please input a valid gender");
        System.out.println("");
        System.out.println("Please enter this person's gender (M/F)");
        gender = keyboard.next().charAt(0);
        gender = Character.toUpperCase(gender); // Convert all inputted character to upper case 
    }


    System.out.println("Please enter whether this person watches the show regularly (Y/N");
    show = keyboard.next().charAt(0);
    show = Character.toUpperCase(show); // Convert show to upper case


    while((show != 'Y') || (show != 'N')){
        System.out.println("Error - input invalid");
        System.out.println("");
        System.out.println("Please enter whether this person watches the show regularly (Y/N");
        show = keyboard.next().charAt(0);
        show = Character.toUpperCase(show); // Convert show to upper case
    }

    System.out.println("Do you want to enter another person's details (Y/N)?");
    details = keyboard.next().charAt(0);
    details = Character.toUpperCase(details);

    while((details != 'Y') || (details != 'N')){
        System.out.println("Error - Invalid input");
        System.out.println("");
        System.out.println("Do you want to enter another person's details (Y/N)?");
        details = keyboard.next().charAt(0);
        details = Character.toUpperCase(details);
    }

Answer 1

条件（gender！=“M”）|（gender！=“F”）永远不能为假。如果gender是'M'，那么gender！='F'将为真，且满足OR条件。如果gender是'F'，那么gender！='M'将为真，并且满足OR条件。

你想要

while (gender != 'M' && gender != 'F') {
    // ...
}

Answer 2

性别M、F或其他有3种可能性。让我们看看

| Gender | gender != 'M' | gender != 'F'| (gender != 'M') || (gender != 'F') |
| 'M'    | False         | True         | True                               | 
| 'F'    | True          | False        | True                               | 
| Other  | True          | True         | True                               | 

这意味着对于任何性别的转换将永远是True